Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films
HfO2-based ferroelectrics show tremendous potential for applications in computing technologies, but questions remain as to what dictates the stabilization of the desired phase. Here, it is demonstrated that the substrate the film is grown on is more influential than factors such as thickness, defect...
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| Format: | Article |
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AIP Publishing LLC
2025-01-01
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| Series: | APL Materials |
| Online Access: | http://dx.doi.org/10.1063/5.0243530 |
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| author | Jesse Schimpf Wang Zhang Mahir Manna Sandhya Susarla Xue-Zeng Lu James M. Rondinelli Lane W. Martin |
| author_facet | Jesse Schimpf Wang Zhang Mahir Manna Sandhya Susarla Xue-Zeng Lu James M. Rondinelli Lane W. Martin |
| author_sort | Jesse Schimpf |
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| description | HfO2-based ferroelectrics show tremendous potential for applications in computing technologies, but questions remain as to what dictates the stabilization of the desired phase. Here, it is demonstrated that the substrate the film is grown on is more influential than factors such as thickness, defect content, and strain. The presence of different possible polymorphs of Hf0.5Zr0.5O2 are observed to vary widely for different substrate materials—with La0.67Sr0.33MnO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and Al2O3 being (more) optimal for stabilizing the ferroelectric-orthorhombic phase. This substrate effect is found to be more influential than any changes observed from varying the film thickness (7.5–60 nm), deposition environment (oxygen vs argon), and annealing temperature (400–600 °C) in vacuum (10−5 Torr). X-ray diffraction and scanning transmission electron microscopy verify the phases present, and capacitor-based studies reveal ferroelectric behavior (or lack thereof) consistent with the phases observed. First-principles calculations suggest that forming oxygen vacancies in Hf0.5Zr0.5O2 lowers its work function, driving electrons away and helping to stabilize the ferroelectric phase. Substrates with a high work function (e.g., La0.67Sr0.33MnO3) facilitate this electron transfer but must also have sufficient ion conductivity to support oxygen-vacancy formation in Hf0.5Zr0.5O2. Together, these observations help clarify key factors essential to the stabilization of HfO2-based ferroelectrics. |
| format | Article |
| id | doaj-art-649e91f71cbf4ce29f4123aab9e0da1c |
| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
| publisher | AIP Publishing LLC |
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| series | APL Materials |
| spelling | doaj-art-649e91f71cbf4ce29f4123aab9e0da1c2025-02-03T16:42:31ZengAIP Publishing LLCAPL Materials2166-532X2025-01-01131011104011104-1310.1063/5.0243530Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin filmsJesse Schimpf0Wang Zhang1Mahir Manna2Sandhya Susarla3Xue-Zeng Lu4James M. Rondinelli5Lane W. Martin6Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USAKey Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People’s Republic of ChinaSchool for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USASchool for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USAKey Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, People’s Republic of ChinaDepartment of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USADepartments of Materials Science and Nanoengineering, Chemistry, and Physics and Astronomy and the Rice Advanced Materials Institute, Rice University, Houston, Texas 77005, USAHfO2-based ferroelectrics show tremendous potential for applications in computing technologies, but questions remain as to what dictates the stabilization of the desired phase. Here, it is demonstrated that the substrate the film is grown on is more influential than factors such as thickness, defect content, and strain. The presence of different possible polymorphs of Hf0.5Zr0.5O2 are observed to vary widely for different substrate materials—with La0.67Sr0.33MnO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and Al2O3 being (more) optimal for stabilizing the ferroelectric-orthorhombic phase. This substrate effect is found to be more influential than any changes observed from varying the film thickness (7.5–60 nm), deposition environment (oxygen vs argon), and annealing temperature (400–600 °C) in vacuum (10−5 Torr). X-ray diffraction and scanning transmission electron microscopy verify the phases present, and capacitor-based studies reveal ferroelectric behavior (or lack thereof) consistent with the phases observed. First-principles calculations suggest that forming oxygen vacancies in Hf0.5Zr0.5O2 lowers its work function, driving electrons away and helping to stabilize the ferroelectric phase. Substrates with a high work function (e.g., La0.67Sr0.33MnO3) facilitate this electron transfer but must also have sufficient ion conductivity to support oxygen-vacancy formation in Hf0.5Zr0.5O2. Together, these observations help clarify key factors essential to the stabilization of HfO2-based ferroelectrics.http://dx.doi.org/10.1063/5.0243530 |
| spellingShingle | Jesse Schimpf Wang Zhang Mahir Manna Sandhya Susarla Xue-Zeng Lu James M. Rondinelli Lane W. Martin Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films APL Materials |
| title | Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films |
| title_full | Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films |
| title_fullStr | Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films |
| title_full_unstemmed | Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films |
| title_short | Interface effects in the phase determination of Hf0.5Zr0.5O2 epitaxial thin films |
| title_sort | interface effects in the phase determination of hf0 5zr0 5o2 epitaxial thin films |
| url | http://dx.doi.org/10.1063/5.0243530 |
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